As a connector having the above-described check function, there is a connector described in PTL 1 for example. The connector described in PTL 1 is structured so that a retainer, which is stretched out by a spool portion (annular protrusion) of a pipe, is slid towards a pipe insertion hole, in a direction opposite to the pipe-insertion direction, with an elastic restoring force of the retainer restoring its original shape, and with the slide of the retainer, it is possible to push in a checker from a temporary stopping position to a completely inserted position of the connector main body.
With this, the retainer moves towards the pipe insertion hole, in a direction opposite to the pipe-insertion direction. Therefore, there is no need of providing a space for accommodating the retainer, in a farther inside of the connector main body relative to the pipe-insertion direction. Therefore, the length of the connector main body is reduced (the connector main body is made compact).